I can eventually install the plugins but it is now a longer process because it includes more steps:

1. Click on Install Now
2. Click OK to Are you sure you want to install this plugin
3. At Connection Information page enter credentials and click on Proceed
4.Goes to blank screen
5.Wait and see nothing happen
6.Click on Return arrow to return to previous page
7.End up again at Connection Information page
8. Enter credentials
9. Click on Proceed
10. Plugin installs correctly

This happens on a few of my sites but not all ( I have a dozen or so). Steps 4,5,6 should not be necessary and normally aren’t.